The bottom two sections are completely dry and are ready for further weathering. My first addition is to add rust on the ballast directly underneath the tracks like this in reality:
I did two tests:
- Wash with a brush
- Airbrush
The wash is at the bottom and the airbrush at the top:
From further away, the difference is quite obvious:
The effect with the airbrush is more convincing, more homogeneous and uniform.